Hi everyone,

I have a very frustrating problem, and I have been through almost all of the posts on here relating to my problem, and nothing I have read has yet solved my problem.

My rig is a 2000 Chevrolet Blazer LS with the 4.3 "w" engine, auto transmission.

I bought this rig about 6 months ago with 161k on it, it had been very well maintained it's whole life (you can tell, this rig has been taken care of). For the first 5 months it was a beauty to drive - everything (almost) worked perfect, and I had no trouble with it - loved it! Now I have a big problem, which I will go into in the next paragraph.

The problem I am having is that the blazer will start up, run very strong for maybe 10 minutes...you could burn the tires off the back if you wanted to. After 5-10 minutes it starts to gradually lose power, and eventually loses ALL engine power unless or until I put it in neutral, shut the engine off and leave it off for 5 seconds, then start it again. After that I have some power back and can keep going just fine for about 5 minutes, then it happens again. It all started when I replaced the fuel pump, it was losing power and the pump sounded horrible. I replaced the pump and fuel filter. It ran GREAT for 2 days, then it came up with this problem where it loses power. The only codes in the computer are the Secondary Air Injection malfunction, and an 02 sensor (bank 1 sensor 3, if I recall correctly) which I unplugged to put it in limp mode for diagnosis, which didn't make the blazer run any better. After that I put a new one in, and the code has been gone, but the blazer still runs like crap. I have checked the CAT, fuel pressure, done a complete tune up, including plugs, wires, cap, rotor, air filter, fuel filter. I also, as I stated before, put a new fuel pump in. I put a new computer in, as the gauges were doing some funny things and I figured it was the computer (it was). So all that stuff is ruled out. I am now tearing it apart to do the Fuel Pressure Regulator, as I think this may be the problem...but I'm not sure.

While I was tearing apart the top end, I came across the Canister Purge Valve (?) Delphi # 1997277 which, when unplugged, poured out rust everywhere. Maybe this is part of my problem??? I'm not sure exactly, but I will continue to pull the top end apart and check the fuel pressure regulator.

Please help me, any suggestions are welcome. I work 2 jobs and I really need this rig for my work, but I had to buy a small car ($300 car) to get me around until the blazer can be available again. I really need the 4WD for my job since I drive in muddy places a-lot. So having a car really isn't doing the trick, as you can imagine.

Thanks for reading this. Hope someone can come up with a solution!!

Josh

EDIT: I forgot to mention that when the problem of no power starts occuring, and you either put the rig in park or neutral and put the gas pedal to the floor, it will only rev up to about 2500-3000 rpms and hesitate, sometimes popping and backfiring. It sounds like it is starving its'self of fuel or something. As soon as I restart the vehicle, it will rev up fine for a bit before the problem comes back.

 

I would make sure the EGR valve is cleaned out and have the ignition coil tested.

 

Thanks for the suggestion...I forgot to check the EGR valve, so I will do that now. I did buy a used coil for $50, swapped it, and there was no change. I forgot I had bought that.

Ok so I just got done pulling apart the top, and I have figured out that this injector unit is the old style one, not the upgraded one. I also have taken off the FPR, and the screen behind it had quite abit of dirt on it...I mean gas could still easily get through, but it had some dirt on it. So I'm assuming that the dirty screen + a possibly bad FPR could cause the hesitation and stalling out...as well as the starving fuel issue. Here are some pictures.

 

**UPDATE**

I just finished putting back together my blazer - I replaced the Fuel Pressure Regulator. This did NOT fix the problem. For the first few minutes it ran like crap, then it cleared up and had more power than it's had since I owned it. Then it went back to the same old same old bogging down. I've gone through everything, it seems, and nothing has solved my problem.

I may end up taking it into a dealership if I can't figure it out soon - this is frustrating!

 

Sounds like one or more sensors are not feeding the proper information to the PCM. Once the PCM enters closed loop operation (your 5-10 minutes from cold start and 5 minutes from hot start), it freaks out.

For starters, when was the last full tune up (plugs, wires, cap, & rotor)? Have you thought about replacing the upstream O2 sensors (B1S1 & B2S1 which are between the exhaust manifolds on the engine and the 'y' in the y-pipe or before the pre-cats if so equiped)?

To diagnose it properly, you really should have someone with the proper diagnostic tools take a look at it. You could throw parts until your wallet is empty and still not hit the right one.

 

Thanks for the input - I plan on taking it to a garage this week and dropping it off for diagnosis. I broke (yes, broke) the MAP sensor in attempting to take it out for inspection, so I bought a new one of those (another $50 bucks). No difference in the way it runs. I cleaned the EGR, took apart and cleaned all the other sensors I could find. I didn't replace any 02 sensors yet, but I did unplug them to see if driving while unplugged (In open loop mode) would solve anything, per a suggestion from a certified mechanic. There was no change in the way it ran, so I'm assuming they aren't a problem? Unless of course the mechanic was wrong. He said if I unplug them it will run better if they are the problem.

I'll try to get it to a garage this week, and hope the outcome is favorable.

Thanks again.

 

when i got that mine was unplugged. its rite next to ur oil filter. u mite have to take the whole cover off to get to it. it has two vacum lines going to it. its small but u cant miss it. i would also check for vacum loss.

 

I read your entire thread. And everything you experienced is what im experiencing! Ive basically replaced as much as you have. This is so frustrating!!!!!
It runs fine at idle but then past idle it looses power, acts like it wants to die out and then backfires. Ive replaced the fuel pressure regulator to and still no help to the problem. Im going to test vacuum and compression tomoro. The only code that i have to work with is a crankshaft position sensor code.
Ive also tested the fuel pressure and here are my readings
key on - 60psi
key on, fuel pump off- holds at 52-54psi
after ten minutes it drops into the low 40's
Could I have a leakdown somewhere?
Can you, if you dont mind, let me know what your mechanic says?
Any help would be great! Thanks

2001 Chevy Blazer 4.3L Vortec 4x4

 

Have been struggling with a similar problem on my wife's 2000 Blazer LT for several weeks.
Runs fine for a few minutes then lack of power and no revs.
Bought ELM327 diagnostic software and Haynes manual, no fault codes showing and everything looks normal, so have been checking everything suggested in the manual, when I got to EGR valve the manual said there was no way to test it without specialised equipment so in desperation I took the wires off, the engine now runs normally the full 190 hp is there all the time.
Can I clean the valve or do I need to replace it?
Hope this helps you.